In general, when a photographic image is printed, the printed image is required to have high glossiness so that the resultant color image has good clearness and high class looking. In attempting to produce such glossy images, techniques of controlling the glossiness of images using a transparent toner have been proposed and used. However, the glossiness (glossiness GS measured at an angle of 60°) of images prepared by using such a transparent toner is 70% at most. In attempting to produce images having glossiness higher than 70%, a print controlling device which heats a recording sheet having a toner image thereon while applying pressure to the recording sheet set on a belt to smooth the surface of the toner image is proposed.
However, a business document, which typically consists of character images, is required to have low glossiness so that the character images are legible. When a photographic image and a character image are formed on one recording sheet using such a print controlling device as mentioned above, the glossing device of the print controlling device has to perform the glossing operation in such a manner that the photographic image is glossed, and the character image is not glossed.
The belt of the print controlling device used for glossing images has so smooth surface that a recording sheet easily slips on the belt, and therefore it is difficult to determine the position of the photographic image on the recording sheet (i.e., the position of a portion of the recording sheet to be subjected to a glossing treatment).
For these reasons, the inventors recognized that there is a need for an image glossing apparatus which can precisely determine the position of a portion of the recording sheet to be subjected to a glossing treatment to perform a glossing treatment only on the image to be glossed.